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Propositional Resolution
Part 2
Short Review
Professor Anita Wasilewska
CSE 352 Artificial Intelligence

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*Sign up*GOAL:
Use Resolution to prove/ disapprove
|= A
PROCEDURE
Step 1:
Write
¬A
and transform ¬A info set of
clauses
CL
{¬A}
using
Transformation rules
.
Step 2:
Consider
CL
{¬A}
and look at if you can get a
deduction of {} from
CL
{¬A}
ANSWER
1.
CL
{¬A}
⊢
R
{}
–
Yes,
|= A
2
.
CL
{¬A}
⊢
{} (i.e. you never get {}) –
No, |= A

Rules of transformation
•
Rules of transformation of a formula
A
into a
logically equivalent set of clauses
CL
A
•
Rule U:
(AUB)
A,B
+ Information
What “Information” mean?
Example:
a, b, (a U ¬( a=> b)), ¬c
a, b, a ,¬( a=> b), ¬c
a,b, ¬c is Information
Rule (U)
:
I , (AUB), J
I, A, B, J
I,J
--- Information

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